I've taken a list of English words, and examined each of them to see what they sound like (using the PHP metaphone function). This page lists the most common metaphone codes, along with their words. You can also search for a word of your own, and see which words sound similar - and which ones rhyme, and which ones alliterate.
rapeseed reposed repassed reopposed rapist ripest ropiest roupiest repast ripost
gapeseed rapeseed peised appeased
rapes raps trapezii trapezia trapeze trapes drapes grapes crapes craps fraps wraps ropes ripes reaps rappees traps